Input devices including proximity sensor devices (also commonly referred to as touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by an input surface, in which the proximity sensor device determines the presence, location, and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones).
Some input devices also have the ability to detect forces applied to the input surface in addition to determining positional information for input objects interacting with a sensing region of the input surface. For example, one or more force sensors positioned beneath the input surface may detect the amount of force exerted on the input surface based, at least in part, on a movement or deflection of the input surface under the applied force. Thus, the flexibility of the material used for the input surface (such as a cover screen or lens) may affect the accuracy and/or sensitivity of the force sensors. More specifically, the relative flexibility of the input surface may vary with respect to its surface area. For example, an input surface with a relatively small surface area may be harder to depress or deform (e.g., under external forces) than an input surface having a larger surface area (e.g., assuming both input surfaces are made frame the same material, having the same uniform thickness).
Some modern input devices have curved input surfaces. For example, the cover lens may wrap (or curve) around the sides of a mobile device to detect inputs on the edges of the mobile device and/or display screen. However, the edges of the mobile device may have a significantly smaller surface area than the front surface of the mobile device. Thus, it may be desirable to detect forces exerted in regions of an input surface having different surface areas.